Body types, or somatotypes, are a classification system originally developed by psychologist William Sheldon, who grouped physiques into three broad categories: ectomorph, mesomorph and endomorph. Understanding what makes each type distinct helps explain what an endomorphic body actually looks like.
An ectomorph child is naturally slim and long-limbed, with a fast metabolism that makes it hard to gain either fat or muscle. A mesomorph child has a naturally athletic, muscular build and tends to gain muscle easily while staying relatively lean. An endomorph child sits at the opposite end from the ectomorph: they have a rounder, softer frame, a wider bone structure, and a body that stores fat readily, giving them a fuller build even without excess eating.
This tendency comes from a comparatively slower metabolic rate, meaning energy from food is converted to fat more readily than it is burned off, which is why endomorphic children can put on weight faster than their ectomorphic or mesomorphic peers if their diet and activity levels aren't matched to this tendency.
Therefore, an endomorphic body type in children refers to a rounded, soft physique with a naturally higher body fat percentage and slower metabolism, contrasting with the lean ectomorph and the muscular mesomorph.